The contents of chemical reactors may be intermixed by means of stirrers whose drive for the stirring device is mounted outside of the reactor vessel. Torque is transmitted from the motor to the stirrer by means of a shaft which passes through the vessel wall. The shaft may be sealed by a gland. The gland gives rise to problems regarding tightness, so that so-called glandless stirring devices (motor-driven magnetically-coupled stirrers) are frequently used at pressures of &lt;5 MPa. In this case the shaft of the stirring device is surrounded by a tube which is closed on one side. The open tube end is connected to the high-pressure reactor. Permanent magnets are mounted on the part of the stirring shaft which is disposed in the tube outside of the reactor. A cylindrical part is secured such that it can rotate about the tube and also has magnets mounted on its inside. A motor drives the cylindrical part. Torque is transmitted via the magnets through the tube to the stirrer shaft. The space between the tube and the stirrer shaft is filled with the medium contained in the high-pressure reactor. It represents a dead space in which deposits, secondary reactions and unintended phase transitions (e.g. condensation) may occur. Uniform temperature regulation of the content of the high-pressure reactor is made more difficult by this dead space.
Another possible way of mixing the contents of a reactor lies in using a motor-free, magnetically-coupled stirrer at the end face of a cylindrical reactor (cf. U.S. Pat. No. 4,199,265). A bar magnet serves as a stirring fish which rotates unmounted in the reactor, with a rotating magnetic field being produced by a plurality of electromagnets mounted outside the reactor on the end face. One disadvantage of using a stirrer of this kind in a high-pressure reactor with a window lies in the fact that one end face of the vessel is occupied and not available for a window which covers the entire cross section of the reactor. In this connection it must be borne in mind that the second end face is usually required for a bellows or for a second window (e.g. for light irradiation). Another disadvantage lies in the fact that the bar magnet serving as a stirrer is not mounted. This means that the bar magnet may take up a position in which it is no longer within the bounds of the rotating magnetic field. The bar magnet also makes it impossible to obtain an unhampered view along the longitudinal axis of the reactor, and this represents a serious limitation for the observation of phase transitions and critical points.
The object of the invention is to develop a reactor for chemical reactions which has the following features:
1. It should be possible to inspect the entire cell interior of the reactor through at least one visual observation window in order to be able to observe phase changes and critical points while a reaction is taking place. The stirrer must in this respect be formed such that each location in the cell can be observed, at least over a period of time. PA1 2. Satisfactory intermixing is a necessity for the entire interior. PA1 3. There should not be any dead spaces in which deposits or condensation may occur. PA1 No dead spaces are introduced into the reactor by the stirring device. PA1 By forming the rotor as a ring or tubular piece which is concentric with the vessel wall, it is possible to achieve an unobstructed view or transmission through the reactor interior for measurement and observation purposes. PA1 There is a reduction in the overall number of seals required, so that there are fewer sealing problems. PA1 On account of the simple and sturdy structure, the time expended on assembling, dismantling and cleaning the reactor can be reduced. PA1 Improved temperature regulation is also possible on account of the relatively simple reactor cell geometry.
A motor-driven stirring device inevitably has dead spaces. A motor-free stirring device cannot be provided at an end face on account of the fact that one end face, which is required for the window, is occupied. A non-mounted stirring fish may settle and obstruct the longitudinal axis of the cell. It is for these reasons that the chemical industry requires an improved high-pressure reactor with a magnetic stirrer which meets the above requirements.